Swallowing Evaluation and Treatment: Efficiency, Accuracy, and Objectivity

This application note is a cursory review of how our clinic has used the Kay Swallowing Workstation. The system is discussed in relation to three important areas of dysphagia management: 1) Diagnostic objectivity, accuracy and reliability; 2) Integration of related body systems into evaluation and treatment methods; and 3) Measurement and documentation of swallowing treatment outcomes.

Diagnostic Objectivity, Accuracy and Reliability

An accurate assessment of swallowing function requires instrumentation that allows ease of operation, clear visual and audio signals, capacity for temporal measurement, observation of bolus movement related to structural movement, and portability (Logemann, 1983; Martin, 1987). The Swallowing Workstation assists us in fulfilling these needs. The system’s components are housed in a compartmentalized, mobile cart which can be used in swallowing evaluation and treatment protocols.

The video recording equipment allows for on-line recording of the video signal emitted from the fluoroscopic viewing monitor in the radiology suite, and stores on videotape (or selected image sequences on disk) the information obtained during the modified barium swallowing studies for immediate or later analysis. An event marker feature allows clinicians to mark any on-line events during the evaluation that may lend diagnostic and prognostic utility during treatment planning such as, indicating spontaneous dry swallows or cued dry swallows that were necessary to safely and efficiently clear the oropharynx or supraglottic larynx from misdirected or residue contrast material. Subtle throat clearing, anticipatory gagging behavior or coughing that occur at various bolus positions throughout the swallow may also be delineated.

Bolus texture and volume impact the timing and duration of swallowing mechanics, and accurate interpretation of swallowing function is dependent upon control of these variables throughout the study (Cook, Dodds, Dantas, Kern, Massey, Shaker, and Hogan, 1989). The Workstation incorporates a video log feature that allows clinicians to identify the bolus texture and volume administered for each swallow series. Examiners are able to quickly reference the optimal bolus variables that resulted in maximal swallowing safety and efficiency during their analysis and consequently formulate appropriate bolus texture and volume feeding recommendations. Further, identification of all bolus volumes and textures given during the examination should be a continuous quality assurance monitor that checks and balances entry level clinician’s decision-making skills during the modified barium swallow evaluation.

The purpose of the evaluation is to achieve maximum information with minimum degree of radiation exposure. This can occur only if the clinician selects the appropriate bolus texture on the subsequent swallow based upon careful observation of swallowing behavior on the preceding swallow. For both clinical and research purposes, it is necessary to avoid prolonged exposure from redundant serial swallows of the same bolus texture and volume that do not contribute to diagnostic yield.

The clinical approach to the treatment of swallowing disorders must be based on an objective and accurate examination. The Kay system provides a favorable videofluoroscopic image recording that is free from substantial distortion during freeze-frame and slow-motion analysis. Component by component inspection of overlapping swallowing events is permitted, and the trained examiner is able to relate bolus movement to structural movement that results in precise and reliable summation of the patient’s problem profile (Martin, 1994). Clinicians may also include a temporal analysis of selected swallowing parameters by recording onset and offset times that are quickly computed and documented into the patient’s file.

In days past, attempts to locate the position of a patient’s previous swallowing evaluation for comparison with repeat studies resulted in arduous manual fast-forwarding and auto-reverse searching on volumes of video tapes. This inefficient system partially paralyzed operations in busy clinics that rely on centralized scheduling of multiple examinations and appointments. Further, this inefficiency adds to nonproductive clinical time in an era when clinical productivity is highly scrutinized by hospital administrators. In contrast to previous practices, the Kay system now allows for easy archiving of patient examination data, and presents a composite of all repeat examinations which can be retrieved efficiently.

Integration of Related Body Systems

Repeated investigations have shown a coordinated temporal relationship between breathing and swallowing functions in healthy adults (Issa and Porostocky, 1989; Selley, Flack, Ellis, and Brooks, 1989; Martin, Logemann, Shaker, and Dodds, 1994; Selley, Ellis, Flack, Bayliss, and Pearce, 1994). The results of this work have led clinicians to consider the coordination of breathing and swallowing during the swallowing evaluation process. Historically, the integration of multiple and time-linked physiologic signals required cumbersome and numerous pieces of equipment, and exposed the patient to excessive physiologic loading while wearing the various apparatuses. However, the application of the Swallowing Workstation permits synchronization, on-line display, videotape recording and digitization of several physiologic signals during the time of the modified barium swallowing evaluation.

Most healthy individuals habitually initiate the pharyngeal swallow near the beginning of an apneic interval (x = 1.0 s) that often interrupts the expiratory limb of the respiratory cycle, and the breathing patterns remain fairly regular pre- and post-swallow (Martin et al., 1994). In patients with chronic lung disease; however, we have found aberrant respiratory-swallow coordination including initiating the pharyngeal swallow during an inspiratory maneuver, delayed laryngeal closure, and interrupted apneic intervals with associated aspiration (Shaker, Li, Junlong, et al., 1992; Martin, Haynes, O’Connor, et al., 1994; Martin and Robbins, 1995). These aberrant respiratory-swallowing patterns are often seen during exacerbation of the pulmonary disease, and have been shown to improve over time with medications and by controlling bolus volume, bolus texture, eating and drinking rates.

At the time of the modified barium swallowing evaluation, the clinician is now able to obtain swallow-related respiratory information by placing a nasal cannula on the patient that displays the phase of respiration and swallow apneic period on the videoscreen. Any discoordination of the breathing pattern can be documented and visually linked in time with the displayed swallowing activity. The examiner can temporally relate the onset of swallow apnea with pertinent physiology such as airway closure and reopening. This information carries important prognostic information in the planning of swallowing therapy. If an individual is unable to maintain apnea necessary for complete airway closure and swallow completion, he or she will be unable to perform maneuvers such as the Mendelsohn or supraglottic swallow that require a prolonged breath-hold (Logemann, 1983; Martin, Logemann, Shaker, and Dodds, 1993). If the patient is a mouth breather or suffers from nasal congestion, instruments that record respiratory chest and abdominal expansion may be adapted and coupled to the Workstation by way of an auxiliary input channel. Following the examination, the patient learns to maintain a regular breathing cycle that can be displayed on the Kay video monitor during the subsequent therapy session. By linking the EMG signal (e.g. indicating the onset of swallow activity) with the respiratory trace, the patient is able to learn to close the airway and stop breathing prior to the swallowing attempt, and to resume breathing at the completion of the swallow.

Clinicians are often tempted to group various disease categories into predictable problem types based on previous experiences with the diagnostic category. However, caution must be taken because of potential patient variability, as well as between and within normal subject variation in swallowing behavior (Lof and Robbins, 1990; Rendell and Spiro, 1994). Based on the individualized swallowing problem profile presented by the patient, the Kay system allows clinicians to configure the video screen to accommodate whatever physiologic signals may be diagnostically and therapeutically relevant.

Measurement and Documentation of Treatment Outcomes

The selection of strategies for the treatment of dysphagia must be based on objective scrutiny of the swallowing mechanism during the diagnostic procedure. The effectiveness of these strategies should be tried at the time of the evaluation whenever clinically feasible. Physiotherapeutic exercises have been applied to the striated musculature of the aerodigestive tract in a manner similar to their application for impaired musculature of the upper and lower extremities. The primary goal of these exercises is to facilitate the motor unit and improve strength, range and integration of muscle movement into the swallowing act (Martin, 1994). Increased strength of muscle contraction has been measured by increases in signal amplitude with electromyography of specific muscle groups (Huckabee, 1992; Gupta, Reddy and Canilang, 1996) or have been inferred from intraoral or pharyngeal pressure recordings (Frohlich, Ingervall, and Schmoker, 1993; Pouderoux and Kahrilas, 1995; Robbins, Goel, Somodi, and Luschei, 1995). Increases in range of movement have been recorded by assigning numeric values on relatively arbitrary rating scales or by plotting movement curves that relate to relative distances of structural movements over time on digitized swallowing images (Logemann, Kahrilas, Begelman, Dodds, and Pauloski, 1989; Dengel, Robbins, and Rosenbeck, 1991). These methodologies to date have shown validity in the research laboratory, but have not proven highly practical in many clinical settings because of the expensive nature of the required equipment, or because of the lack of knowledge required in coupling and operating the various pieces of equipment. Consequently, clinicians have been forced to rely on their clinical impressions and unsystematic approach of trial and error through use of physiotherapeutic techniques that seem to have shown some past success in clinical practice. However, third party payers are no longer settling for subjective therapy impressions of improved patient swallowing function. Payers, as well as consumers, are demanding quantification of treatment outcomes in order to justify enrollment in and reimbursement for therapy. Therefore, it has become a clinical necessity to be able to objectively document small changes in the focused treatment outcomes, as well as long term functional outcomes. Accurate documentation to referring physicians, clinicians and facilities is critical for ensuring of an appropriate continuum of care once the patient’s leaves the diagnostic session.

The tongue has long been described and shown to be the most mobile element of swallowing function. The tongue assists with bolus containment, bolus propulsion and airway protection (Ardran and Kemp, 1955; Storey, 1976; Logemann, 1983; McConnel, 1988; McConnel, Cerenko, and Mendelsohn, 1988). Voluntary control is a potent modifier of tongue pulsive force and clearing pressure (Pouderoux and Kahrilas, 1995). Application of the Workstation as a therapeutic tool now allows clinicians to objectively measure changes in tongue pressures that indirectly relate to increases in tongue strength. Various tongue bulb arrays have been configured and housed in a comfortable intraoral device that may be used during isolated postures (i.e., elevation and lateralization) and during dry swallows. A graphic display of the generated tongue pressures appears clearly on the screen for patient scrutiny as he or she attempts to match or exceed a target response. Similar visual feedback may be displayed from signals obtained during submental EMG recordings as the patient attempts to maintain extrinsic muscle contraction during a hard swallow or Mendelsohn maneuver. The numeric data from the exercise session is stored to disk and may be printed with an adapted videoprinter to be maintained with the patient’s progress records. Goal-setting may then be based on attaining various pressure or signal displacement levels, and related to functional improvements during eating and drinking throughout the course of treatment.

Conclusion

The Kay Swallowing Workstation has shown to be a practical clinical tool in daily swallowing evaluation and treatment sessions. Continued input from users should result in further refinement of the technology that leads to clinical and research applications in addition to those mentioned above. This instrumentation represents an important contribution to clinicians who are involved in the evolutionary science of dysphagia evaluation and treatment.

References

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Frohlich, K., Ingervall, B., & Schmoker, R. "Influence of surgical tongue reduction on pressure from the tongue on the teeth." Angle Orthodontist, Vol. 63 (3), pp. 191-198, 1993.

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